Mary Shelley wrote Frankenstein in 1815 as the result of a ghost story contest with her husband and two other friends. Only her story has survived.
What makes her story so enduring? We are reading her corrected 1831 edition, by the way.
And look at the title. She called it Frankenstein, and most people think that is the name of the monster that Dr. Victor Frankenstein created. Is the confusion of monster and creator something she intended?